CVE-2026-84128: Vulnerability in Mozilla Firefox
Description
CVE-2026-84128 is a privilege escalation vulnerability in the WebDriver BiDi component of Mozilla Firefox. This vulnerability was fixed in Firefox version 155. The CVSS score is 8.8, indicating a high severity impact. The vulnerability was internally found and addressed as part of a security update that fixed multiple high-impact bugs in Firefox 155. There are no known exploits in the wild. The vendor advisory confirms the fix is included in Firefox 155.
CVSS v3.1
Score 8.8high
Affected software
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-84128 is a privilege escalation vulnerability affecting the WebDriver BiDi component in Mozilla Firefox. It was identified internally and fixed in Firefox 155. The vulnerability allows an attacker to escalate privileges within the affected component. The CVSS v3.1 base score is 8.8 (AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H), indicating network attack vector, low attack complexity, no privileges required, user interaction required, unchanged scope, and high impact on confidentiality, integrity, and availability. The Mozilla advisory MFSA 2026-82 confirms the fix and lists this vulnerability among others resolved in Firefox 155.
Potential Impact
Successful exploitation of this vulnerability could allow an attacker to escalate privileges within the Firefox WebDriver BiDi component, potentially leading to full compromise of the affected process. The high CVSS score reflects significant impact on confidentiality, integrity, and availability. However, there are no reports of active exploitation in the wild. The vulnerability is mitigated by updating to Firefox 155 or later.
Mitigation Recommendations
Mozilla has released an official fix for this vulnerability in Firefox 155. Users and administrators should update affected Firefox installations to version 155 or later to remediate this issue. No additional mitigation steps are required beyond applying the official update.
Technical Details
- Gcve Source
- db.gcve.eu
- Osv Id
- GHSA-3h3x-m88j-vrhj
- Osv Schema Version
- 1.4.0
- Aliases
- ["CVE-2026-84128"]
- Database Specific Severity
- HIGH
- Cvss Version
- 3.1
Threat ID: 6a984571acd9273b496ad269
Added to database: 09/02/2026, 15:49:05 UTC
Last enriched: 09/07/2026, 20:07:17 UTC
Last updated: 10/15/2026, 18:48:24 UTC
Views: 35
Community Reviews
0 reviewsCrowdsource mitigation strategies, share intel context, and vote on the most helpful responses. Sign in to add your voice and help keep defenders ahead.
Want to contribute mitigation steps or threat intel context? Sign in or create an account to join the community discussion.
Actions
Updates to AI analysis require Pro Console access. Upgrade inside Console → Billing.
Need more coverage?
Upgrade to Pro Console for AI refresh and higher limits.
For incident response and remediation, OffSeq services can help resolve threats faster.
Latest Threats
Check if your credentials are on the dark web
Instant breach scanning across billions of leaked records. Free tier available.